Cass, Fleur, and Jack search for survivors from the transporter. A young woman is taken hostage. Meanwhile, Stella and Tate are confronted by an old foe.

Fleur tries to make peace with the ACs. While a whiteout threatens to destroy Forthaven, Cass sets out on an impossible rescue mission.

A troubled AC enters Forthaven and attacks a citizen. Fleur and Cass struggle to contain the situation. The Expeditionaries make a stunning discovery.

An early settler of Carpathia, long believed dead, returns to Forthaven. Cass and Fleur follow him into dangerous unexplored territory. Berger's influence continues to grow. And Tate believes his dead children have returned.

The mystery surrounding three missing Expeditionaries only deepens when one of them returns to Forthaven.

Cass receives an anonymous note that threatens to expose his past. Tipper helps Stella and Tate learn more about the mysterious hostile life form that occupies the planet.